E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Wooden Wall.
When the Greeks sent to Delphi to ask how they were to defond themselves against Xerxes, who had invaded their country, the evasive answer given was to this effect
1
Pallas hath ulged, and Zeus, the sire of all,
Hath safety promised in a wooden wall;
Seed-time and harvest, weeping sires shall tell
How thousands fought at Salamis and fell.
Wooden walls of Old England. The ships of war. We must now say, The iron walls of Old England.